A 3D view on the local gravitational instability of cold gas discs in star-forming galaxies at $0 \lesssim \mathrm{z} \lesssim 5$

Understand

Local gravitational instability (LGI) is considered crucial for regulating star formation and gas turbulence in galaxy discs, especially at high redshift.

• Instability criteria usually assume infinitesimally thin discs or rely on approximations to include the stabilising effect of the gas disc thickness.
• We test a new 3D instability criterion for rotating gas discs that are vertically stratified in an external potential.
• This criterion reads $Q_{\rm3D}<1$, where $Q_{\rm3D}$ is the 3D analogue of the Toomre parameter $Q$.